/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using NHibernate;
using Spring.Util;

namespace Spring.Data.NHibernate.Support;

/// <summary>
/// Holds the references and configuration settings for a <see cref="SessionScope"/> instance.
/// </summary>
public class SessionScopeSettings
{
    /// <summary>
    /// Default value for <see cref="SingleSession"/> property.
    /// </summary>
    public static readonly bool SINGLESESSION_DEFAULT = true;

    /// <summary>
    /// Default value for <see cref="DefaultFlushMode"/> property.
    /// </summary>
    public static readonly FlushMode FLUSHMODE_DEFAULT = FlushMode.Never;

    private ISessionFactory sessionFactory;
    private bool sessionFactoryInitialized;
    private IInterceptor entityInterceptor;
    private bool entityInterceptorInitialized;
    private bool singleSession;
    private FlushMode defaultFlushMode;

    /// <summary>
    /// Initialize a new instance of <see cref="SessionScopeSettings"/> with default values.
    /// </summary>
    /// <remarks>
    /// Calling this constructor from your derived class leaves <see cref="SessionFactory"/> and <see cref="EntityInterceptor"/>
    /// uninitialized. See <see cref="ResolveSessionFactory"/> and <see cref="ResolveEntityInterceptor"/> for more.
    /// </remarks>
    protected SessionScopeSettings()
    {
        this.sessionFactory = null;
        this.sessionFactoryInitialized = false;
        this.entityInterceptor = null;
        this.entityInterceptorInitialized = false;
        this.singleSession = SINGLESESSION_DEFAULT;
        this.defaultFlushMode = FLUSHMODE_DEFAULT;
    }

    /// <summary>
    /// Initialize a new instance of <see cref="SessionScopeSettings"/> with the given sessionFactory
    /// and default values for all other settings.
    /// </summary>
    /// <param name="sessionFactory">
    /// The <see cref="ISessionFactory"/> instance to be used for obtaining <see cref="ISession"/> instances.
    /// </param>
    /// <remarks>
    /// Calling this constructor marks all properties initialized.
    /// </remarks>
    public SessionScopeSettings(ISessionFactory sessionFactory)
        : this(sessionFactory, null, SINGLESESSION_DEFAULT, FLUSHMODE_DEFAULT)
    {
        // noop
        this.entityInterceptorInitialized = false;
    }

    /// <summary>
    /// Initialize a new instance of <see cref="SessionScopeSettings"/> with the given values and references.
    /// </summary>
    /// <param name="sessionFactory">
    /// The <see cref="ISessionFactory"/> instance to be used for obtaining <see cref="ISession"/> instances.
    /// </param>
    /// <param name="entityInterceptor">
    /// Specify the <see cref="IInterceptor"/> to be set on each session provided by the <see cref="SessionScope"/> instance.
    /// </param>
    /// <param name="singleSession">
    /// Set whether to use a single session for each request. See <see cref="SingleSession"/> property for details.
    /// </param>
    /// <param name="defaultFlushMode">
    /// Specify the flushmode to be applied on each session provided by the <see cref="SessionScope"/> instance.
    /// </param>
    /// <remarks>
    /// Calling this constructor marks all properties initialized.
    /// </remarks>
    public SessionScopeSettings(ISessionFactory sessionFactory, IInterceptor entityInterceptor, bool singleSession, FlushMode defaultFlushMode)
    {
        AssertUtils.ArgumentNotNull(sessionFactory, "sessionFactory");

        this.sessionFactory = sessionFactory;
        this.sessionFactoryInitialized = true;
        this.entityInterceptor = entityInterceptor;
        this.entityInterceptorInitialized = true;
        this.singleSession = singleSession;
        this.defaultFlushMode = defaultFlushMode;
    }

    /// <summary>
    /// Gets the configured <see cref="IInterceptor"/> instance to be used.
    /// </summary>
    /// <remarks>
    /// If the entity interceptor is not set by the constructor, this property calls
    /// <see cref="ResolveEntityInterceptor"/> to obtain an instance. This allows derived classes to
    /// override the behaviour of how to obtain the concrete <see cref="IInterceptor"/> instance.
    /// </remarks>
    public IInterceptor EntityInterceptor
    {
        get
        {
            if (!entityInterceptorInitialized)
            {
                return ResolveEntityInterceptor();
            }

            return entityInterceptor;
        }
    }

    /// <summary>
    /// Gets the configured <see cref="ISessionFactory"/> instance to be used.
    /// </summary>
    /// <remarks>
    /// If this property is requested for the first time, <see cref="ResolveSessionFactory"/> is called.
    /// This allows derived classes to override the behaviour of how to obtain the concrete <see cref="ISessionFactory"/> instance.
    /// </remarks>
    /// <exception cref="ArgumentException">If the <see cref="ISessionFactory"/> instance cannot be resolved.</exception>
    public ISessionFactory SessionFactory
    {
        get
        {
            if (!sessionFactoryInitialized)
            {
                sessionFactoryInitialized = true;
                sessionFactory = ResolveSessionFactory();
                if (sessionFactory == null)
                {
                    throw new ArgumentException(string.Format("mandatory SessionFactory not found"));
                }
            }

            return sessionFactory;
        }
    }

    ///<summary>
    /// Set whether to use a single session for each request. Default is "true".
    /// If set to false, each data access operation or transaction will use
    /// its own session (like without Open Session in View). Each of those
    /// sessions will be registered for deferred close, though, actually
    /// processed at request completion.
    /// </summary>
    public bool SingleSession
    {
        get { return singleSession; }
        set { singleSession = value; }
    }

    /// <summary>
    /// Gets or Sets the flushmode to be applied on each newly created session.
    /// </summary>
    /// <remarks>
    /// This property defaults to <see cref="FlushMode.Never"/> to ensure that modifying objects outside the boundaries
    /// of a transaction will not be persisted. It is recommended to not change this value but wrap any modifying operation
    /// within a transaction.
    /// </remarks>
    public FlushMode DefaultFlushMode
    {
        get { return defaultFlushMode; }
        set { defaultFlushMode = value; }
    }

    /// <summary>
    /// Override this method to resolve an <see cref="IInterceptor"/> instance according to your chosen strategy.
    /// </summary>
    protected virtual IInterceptor ResolveEntityInterceptor()
    {
        return null;
    }

    /// <summary>
    /// Override this method to resolve an <see cref="ISessionFactory"/> instance according to your chosen strategy.
    /// </summary>
    protected virtual ISessionFactory ResolveSessionFactory()
    {
        throw new NotSupportedException("you need to override this method to resolve an ISessionFactory instance");
    }
}
